Patent GB-1384649-A (GB)
Title: Automatically and continuously variable transmission
IPC: F16H3/56
Filed: 1972-05-16
Abstract: 1384649 Variable speed gear; electromechanical power transmissions R L BRICOUT 16 May 1972 [21 May 1971 16 Nov 1971 15 March 1972 4 May 1972] 22971/72 Heading F2D  A planet gear, providing steplessly variable ratios by a variable-speed electric motor 61 controlling the relative speed of its elements, comprises three compounded trains, viz an input train I with elements such as a sun 41 and ring gear 42 permanently connected respectively to main input and output shafts 34, 35; a control train II of very high ratio, with a planet carrier 55 driven by the control motor 51 and two suns 54, 58, or ring gears, one, 54, connected to a third element planet carrier 46, of the input train I, and the other, 58, to an element, sun 59, of an intermediate train III, the two remaining elements of which latter, ring gear 49 and planet carrier 50, are connected respectively to the carrier 46 of the input train I and to either the input or output shaft 34 or 45. As shown in Fig. 7, two of these connections to the carrier 46 are made through invariable meshing gear pairs 52, 53 and 46, 48. Due in part to the low efficiency and high multiplication in the control train II, the control motor may be required to have only 1 per cent of the transmitted power and 1 to 3 per cent of the maximum transmitted torque. The motor operates at substantially constant torque in either a driving or braking mode and in either direction, although in the further embodiments below, it drives only, its maximum speed being 24,500 r.p.m. reversely, which occurs on starting. The motor may be a double squirrel cage asynchronous motor the stator of which receives a three-phase supply from an alternator 40 continuously driven by the main input shaft 31, which, in Fig. 7, drives the gear input shaft 34 through a clutched reverse gear 33...37. Due to irreversibility of the high ratio control train II, engagement of both forward and reverse clutches 35, 38 together locks the output shaft for parking. Both electric machines are of low voltage (1 to 5 volts), with aluminium stator conductors. In Fig. 11, not shown, the input train I is a four-element overlapping train, with stepped planets meshing two suns (69, 70), and one input-driven ring gear (67). The control train II, which is irreversible and has a ratio of not less than 100 and preferably between 100 and 150 to 1, has two ring gears (75, 76) of the same diameter but differeing in tooth number by cne, meshing a common planet, the carrier 78 of which is driven by the control motor. Reverse is provided at fixed ratio by an electromagnetically operated clutch-brake (82) which disconnects a sun (81) of the intermediate train III from a ring gear (75) of the control train II and brakes the sun (81) to the fixed casing. In Fig. 15, not shown, in which reverse is not provided, some of the elements of trains I and III are interchanged and the control motor (80<SP>1</SP>) is built into the gear casing coaxial with the output shaft.  On a motor vehicle the speed of the control motor may be controlled by the usual accelerator pedal (93, Fig. 14, not shown), actuating a potentiometer (92) in the field exciting circuit of the alternator 40 which energizes the motor, an output speed responsive governor (96) being provided to short circuit the potentiometer above a predetermined speed on accelerator release to increase the speed ratio for engine braking. For machine tools the alternator excitation is derived from the comparison of the output of an output driven generator with a standard voltage. Graphical solutions for the speed and torque of the gear elements are given. The overall ratio may vary between 9 to 1 and 1 to 1, although overdrive may be provided.